ISOLATION AND CHARACTERIZATION OF THE HUMAN AND MOUSE HOMOLOGS (SUPT4H AND SUPT4H) OF THE YEAST SPT4 GENE

To study gene regulation mediated by chromatin in mammals, we isolated the human (SUPT4H) and murine (Supt4h) counterparts of the yeast gene encoding SPT4; the product of this gene presumably interacts with the products of the mammalian homologues (which we have also cloned) of y east SPT5 and SPT6, thereby modulating chromatin formation and activit y. We isolated two different sized human SUPT4H cDNA clones (1464 and 728 nt) and one murine Supt4h (688 nt) cDNA clone; all three encode th e same 117-amino-acid protein with conservation of the zinc finger mot if found in SPT4. Conservation of this zinc finger motif from yeast to mouse and human implies functional importance. Although the overall s equence homology at the DNA level between the human 728-nt transcript and the murine 688-nt transcript is only 78.4%, the DNA sequence homol ogy is 97.7% within the coding region. At the protein level, the amino acid sequences of the translated murine Supt4h and the human SUPT4H g ene products are identical, The likely functional copy of SUPT4H, whic h has at least two introns, maps to human chromosome 17, with candidat e intronless pseudogenes on chromosomes 2, 12, and 20. Buttressing the hypothesis that this is a gene required constitutively, both the huma n SUPT4H transcripts and the murine Supt4h transcript are expressed wi dely, although not at equal levels (e.g., such as most histones), in a ll fetal and adult tissues that we examined. (C) 1996 Academic Press, Inc.